The use of recombinant DNA probes to group and type orbiviruses. A comparison of Australian and South African isolates.

Under the appropriate conditions, recombinant DNA (rDNA) probes to either RNA segment 2 or segment 6 may be used to mimic the serotyping of bluetongue virus (BTV), but this may be attempted only on isolates originating in the same geographical area. Using an rDNA probe from RNA segment 3, group reactivities between the South African and Australian BTV isolates have been observed within those defined by serological methods, as have cross reactivities within the orbivirus group. Comparative hybridisation data is presented to show that variation within the RNA genome segments of BTV renders rDNA probes of RNA3 inadequate for serogrouping the orbiviruses. However, rDNA probes to RNA3 may be used to delineate the geographical origin of a BTV isolate.